A CAM-Based Signature-Matching Co-processor with Application-Driven Power-Reduction Features

Kazunari INOUE
Hideyuki NODA
Kazutami ARIMOTO
Hans Jurgen MATTAUSCH
Tetsushi KOIDE

Publication
IEICE TRANSACTIONS on Electronics   Vol.E88-C    No.6    pp.1332-1342
Publication Date: 2005/06/01
Online ISSN: 
DOI: 10.1093/ietele/e88-c.6.1332
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Integrated Electronics
Keyword: 
CAM,  TCAM,  signature-matching,  network security,  

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Summary: 
A signature-matching co-processor in 130 nm CMOS technology for application in the network-security field is presented. Two key search technologies, implemented with fully-parallel CAM-based search cores, enable the removal of misused packets from Giga-bit-per-second (G-bps) networks in real-time without disturbing the normal network traffic. The first technology is a thorough search through packet header as well as payload in byte-shifting manner and is capable of detecting viruses, even if they are hidden at an arbitrary position within the packet. A 1.125 Mbit ternary CAM, operated at the speed of 125 Mega-searches per second (M-sps), integrates the primary lookup table for thorough packet search. The second technology applies an additional relational search with programmable logical operations to detect recently appearing more complicated misused packets. A small 192-bit binary CAM operated at 31.25 M-sps is also included for this purpose. Power dissipation, being a major concern of CAM-based application-specific LSIs, is addressed in the light of the signature-matching application, which has a high probability of multiple matches and which doesn't require to mask individual bits of the search word. Consequently, two application-driven power-reduction methods are implemented, namely an improved pipelined search for efficiently reducing power even in the case of a large number of multiple matches, and a search-line encoding for cutting search-line related power dissipation. As a result the signature-matching co-processor features low power dissipation between 0.4 W and 1.1 W for the best case and the worst case search configurations, respectively.